Pneumatic power device



Jly 10, 1945 h lE. DAVID 2,380,152

` 'PNEUMATIC POWER DEVICE Filed April 2, 1942 w1' n v4 INVENTOR.

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ATI'DRN EYS Patented July 10, 1945 UNITED STATES PATENT OFFICE PNEUMATIO POWER DEVICE y Erich David, United States Army Application April 2, 1942, Serial No. 437,450

2 Claims. (Cl. 254-93) My invention relates to mechanical devices for exerting great pressure, lifting or moving heavy or light bodies, and has among its objects and advantages the provision of an improved pneumatic pressure device particularly suitable for jack purposes, wherein novel means are incorporated to provide a pressure-tight construction operating in an efficient manner over long periods of time notwithstanding wear on the relatively movable parts.

In the accompanying drawing:

Figure 1 is a vertical sectional view of the jack; and i Figure 2 is a sectional view taken along the vcause the bladder to expand and lift the piston.

To the bottom end of the piston 96 is secured a soft leather washer 98,-.as by screws 98a, which washer provides a cushion for the bladder 94. I

prefer to shape the bladder-engaging face of the washer 98 with a gentle concaved face 98h.

The piston 96 is slightly smaller diametrically than the corresponding inner dimension of the cylinder '90. The washer S8 contacts with the side wall of the cylinder 9|) and holds the piston 96 against lateral play and maintains the upper end of the bladder 94 out of contact with the inner wall of the cylinder.

A tubular elbow 64 is secured to the bottom end of the bladder 94 through the medium of a ange 66 engaging the inner face of the bladder and a nut 68 threadedly connected with the elbow 64 to press a washer 10 against the bladder and clamp the latter between the washer and the flange. The central portion of the wall 92'D is depressed to provide a recess for the reception of the nut 68 and the washer 10. To the outer end of the elbow 64 is connected a hose 'l2 having a control valve I4 interposed therein. This valve includes a housing 16 having a. vent opening 18 and a rotary plug 86 provided with bores '82 and 84.

A handle, not shown, is attached to the plug to facilitates rotation thereof.

Figure 1 illustrates the valve plug 80 adjusted so as to pass air under pressure into the bladder 94. Rotation of the plug in a clockwise direction to bring the bore 82 into communication with the opening 18 and the section 88 of the hose 12 cuts off the supply of air under pressure and Vents the bladder to the atmosphere so that the piston 28 may descend.

' To the piston 96 is xedly secured an elevating shaft slidably guided in a bearing |02 on a plate |04 threadedly connected at |06 with the upper end of the cylinder Si?. This cylinder is ccnstricted at its upper end to provide a shoulder |08 to limit the upward movement of the piston 96 when the bladder 94 is inated a predetermined amount.

Between the piston 96 and the cover |04 is interposed a compression spring H9 to cause th'e piston to descend in the cylinder 9|) when the air pressure is released from the bladder 94. An eX- tension screw ||2 is threaded into a longitudinal bore l I4 in the shaft |90, which screw is provided with a lifting head l I4. Thus the screw H2 may be adjusted to afford a greater or lesser effective reach for the jack. A hose ||8 connected to the control valve '|4 may be provided with a conventional inner tube iniation valve at its end for connection with an ordinary tire pump.

Without further elaboration, the foregoing will so fully illustrate my invention, that others may,l by applying current knowledge, readily adapt the same for use under various conditions of service.

I claim:

1. A pneumatic jack comprising a hollowcylim drical base provided between its ends with a wall, a cylinder having its lower end positioned in and secured to the base above said wall, a piston slidably mounted in the cylinder and carrying Work engaging means, the piston being slightly smaller diametrically than the corresponding inner dimenson of the cylinder, a bladder within the cylinder below the piston, a washer of softer material located between the piston and bladder and contacting with th'e inner wall of the cylinder and embracing the upper end portion of the bladder, the wall of the base being provided with a central depression, an inating tube for the bladder passing through the side wall of the base and through the depressed portion of the wall of the base, and means for securing the tube to the lower end of the bladder, said means fitting in said depression.

2. A pneumatic jack such as claimed in claim l, wherein the upper portion of the cylinder is slightly reduced to provide an inner shoulder adapted to limit the upward movement of the piston, wherein the upper end ofthe cylinder is closed by a plate provided at its center with inner and outer bearing bosses, wherein the work engaging means of the piston passes through said bosses, and wherein the piston is constantly urged downwardly by a coil spring surrounding said means and bearing against the piston and the plates closing the upper end of the cylinder, the Epper end of the spring surrounding said inner oss.

ERICH DAVID. 

